1. Field of the Invention
The present invention generally relates to an emission spectrophotometer for enabling a solid test material to generate pulse light emission to analyze element content, in particular, to a power supply device of the emission spectrophotometer.
2. Description of Related Art
Generally, during an analysis of a solid test material in an emission spectrophotometer, spark discharge is generally generated between an electrode 7 and a test material 8 by a power supply device 1, as shown in FIG. 1. Then, an emitted light is split into spectrum lights of component elements by using a light splitter 9, the spectrum lights are incident to photomultipliers 10a-10e mounted at positions corresponding to spectrum wavelengths intrinsic to the component elements, and output currents of the photomultipliers are integrated by using detection circuits 11a-11e, such that a spectral intensity of each component element is calculated.
Herein, as each spectral intensity is proportional to the content of each component element, a data processing device 12 converts the spectral intensity of each component element into the content. However, the spark discharge is not always generated in an identical state, and thus non-uniformity is resulted due to the differences of the surface state of the test material, the front end shape and the surface state of the electrode, or the state of the Ar gaseous environment. That is to say, when pinholes or fine cracks exist in the test material, or when the front end shape or the surface state of the electrode is changed due to the adhesion or the fusing of the evaporated material from the test material, or when the purity or the flow quantity of Ar is changed, the state of spark discharge is correspondingly changed, thereby causing the non-uniformity of the spectral intensities of the component elements obtained when the pulse light emission is generated by the test material. Therefore, as described in Patent Document 1, in the prior art, the data processing device 12 eliminates the data when the spectral intensity departs from a normal intensity range and becomes extremely high or low by using the method described below.
In the case of analyzing a solid test material, pulse light emission is generated first, a spectrum light of each component element is detected, and data of a group of spectral intensities as shown in FIG. 5 is stored in a memory device. A histogram of the group of spectral intensities correlating with a main component element as shown in FIG. 6 is plotted based on the data stored in the memory device. For example, if the test material is a steel test material, a histogram of a group of spectral intensities correlating with a main component element Fe is plotted. Then, an average value IAV and a standard deviation σ when the histogram is considered to have a normal distribution are calculated, according to the average value IAV and the standard deviation σ, a pair of upper and lower spectral intensities IAV±kσ (k is a constant) with the average value IAV as a center and determined by the standard deviation σ are set as the threshold. Finally, as for the data of the group of spectral intensities of the component elements stored in the memory device, only the data of the spectral intensity of the main component element which is in the preset threshold range is valid, and the data departing from the threshold range is excluded.
Furthermore, in the prior art, a control circuit 2 of the power supply device 1 of the emission spectrophotometer controls a charging circuit 3, such that an energy set by the data processing device 12 is charged to an electricity accumulating and discharging unit (for example, a condenser) 4. Then, a high voltage transformer drives a circuit 5 to work, such that the high voltage transformer 6 generates a high voltage, and insulation breakdown occurs thereafter between the electrode and the test material. As a result, the energy charged to the electricity accumulating and discharging unit 4 is supplied to the gap between the electrode and the test material.